A wind energy converter is a rotating machine that converts the kinetic energy in wind into electricity and feeds the electricity into the electrical grid.
A wind energy converter generally includes a nacelle disposed on a tower. The nacelle (also called a “gondola”) includes a rotor head equipped with blades, and a main shaft connected to the rotor head, also called hub, that integrally rotates with the rotor head. Moreover, the nacelle can rotate around a vertical axis so as to actively or passively follow the wind direction.
A first type of nacelle further includes a gear box connected to the main shaft, which rotates upon receiving the wind power supplied to the blades, and a generator driven by an output shaft from the gear box. According to the wind energy converter having this structure, the rotor head equipped with the blades converts wind power into a torque, and the main shaft rotates to generate a first rotational speed. The first rotational speed is increased via the gear box connected to the main shaft, and a corresponding second larger rotational speed is transmitted to the rotor of the generator.
A second type of nacelle, which lacks a gear box, uses direct drive turbines with AC generators having a variable frequency. Special high power electronics convert this variable frequency to constant frequency for transmission on the grid.
In present wind energy converters, the nacelle must ultimately be on top of a tower. This often requires lifting the nacelle, or its constituent parts, using a crane. Such a task is quite difficult and complex because the components are massive.